1. Field of Invention
This invention relates to a device for preparing a composition at preselected temperatures, and specifically to a semi-frozen food preparation apparatus for preparing and dispensing soft-serve ice cream or similar foods.
2. Description of the Relevant Art
There are known soft-serve ice cream machines. For example, Helwege U.S. Pat. No. 1,942,696 discloses an ice cream freezer wherein brine liquid flows downwardly, by gravitational means, along the inner sides thereof so as to maintain freezing conditions of the freezer. Helwege, however, fails to disclose a device which maintains substantially uniform temperatures along the surface of the container unit, or a device which is easily cleaned.
Harker U.S. Re. Pat. No. 27,019 and U.S. Pat. No. 3,298,190 disclose a frozen confection machine having internal sensing mechanisms, but fail to disclose a device having means for thoroughly mixing compositions throughout the container, for providing a substantially uniform temperature thereto, for easily draining and cleaning the container, or for substantially completely scraping compositions from the inner surface of the container.
Beck U.S. Pat. No. 4,732,013 discloses a freezer having a helical scraper. Beck, however, fails to disclose a device having means for mixing and/or aerating a composition located in a central portion of the container, means for efficiently pushing the composition towards the dispensing port as it is being mixed, or means for maintaining the container in a substantially uniform temperature.
Keyes U.S. Pat. Nos. 3,729,177 and 3,898,866 disclose a pump and cleaning apparatus for frozen confection food machines, but fail to disclose a confection food apparatus having means for efficiently mixing and aerating confection compositions, scraping confection compositions from the inner container surface, or urging compositions towards a discharge port.
Wright U.S. Pat. No. 5,205,129 discloses an apparatus having dual freezing chambers operated from a single motor, and having temperature sensors located within each chamber.